The USGS has confirmed a magnitude 4.5 earthquake with its epicentre 269 km SSE of Alo, Wallis and Futuna, occurring at 21:53 UTC on Tuesday, June 23, 2026. The event's focal depth — 408.9 km — is a key factor in understanding how this earthquake was experienced at the surface.
Why Depth Matters
At a focal depth of 408.9 km, this is a deep earthquake (below 300 km), occurring well within Earth's mantle. Deep earthquakes are a distinctive feature of subduction zones where cold oceanic crust descends into the mantle. Despite the large magnitude, the extreme depth means surface shaking is distributed over a vast area and is considerably less intense at any single point than a shallow event of equivalent magnitude.
Depth is one of the most critical but least discussed parameters of any earthquake. Two earthquakes of identical magnitude can have dramatically different surface effects depending on how deep the rupture originates. Significant damage can occur to vulnerable structures — particularly unreinforced masonry, old adobe buildings, and poorly maintained older construction. Well-engineered modern buildings are designed to withstand this level of shaking with minimal structural impact, though contents may shift and non-structural elements (ceilings, partitions) can be damaged.
Magnitude 4.5: What the Science Says
On the moment magnitude scale, 4.5 represents a moderate earthquake. Moderate earthquakes are felt by virtually everyone near the epicentre. Strong shaking lasting 10–30 seconds can topple unsecured items, crack plaster, and cause poorly anchored objects to fall. Aftershocks are common following moderate events.
A magnitude 4.5 earthquake releases approximately roughly 500 tonnes of TNT of energy. For comparison, this exceeds the energy released by most conventional explosive events and is sufficient to shift tectonic stress in measurable ways across a wide region.
Tectonic Setting
This area sits within a seismically active zone where tectonic stresses periodically build and are released as earthquakes. Global seismic monitoring networks ensure that even remote events are rapidly detected and characterised.
This region's seismic history is an important reminder that earthquake risk is a long-term reality that requires sustained preparedness. Earthquake science has advanced enormously over the past century, with modern seismograph networks capable of detecting and locating events anywhere on Earth within minutes. However, predicting exactly when and where the next earthquake will strike remains one of science's great unsolved challenges.
Practical Safety Information
Regardless of the earthquake's depth or magnitude, standard safety procedures apply. Understanding the type of building you live or work in is one of the most important steps in earthquake preparedness. Older unreinforced masonry buildings and soft-storey apartment buildings are significantly more vulnerable than modern reinforced concrete or steel-frame structures. If you have concerns, consult a structural engineer.
During and after an earthquake, follow instructions from official civil protection, emergency services, and government authorities. Avoid spreading unverified information on social media. Official channels provide the most reliable information about aftershock risk, evacuation orders, and available assistance.
Local civil protection agencies and emergency services are the primary authorities during and after an earthquake. Following official guidance, maintaining an emergency kit, and knowing Drop–Cover–Hold On procedures are universally applicable precautions.
Track This Event
All seismic data for this event is being updated in real time as the USGS refines its measurements. Initial magnitude and depth estimates are sometimes revised as more seismograph stations report in — a process that typically completes within hours of the event. Follow updates on our live earthquake map and consider submitting a felt report if you experienced this earthquake directly.
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